There is a need for high-speed cost effective optical transmitters which can operate as parallel communications data links. The primary function of the optical transmitter is to translate electrical signals into optical signals which are carried over a fiber optic path. The optical transmitter includes an optoelectronic device, such as a vertical cavity surface emitting laser (VCSEL).
Connection of the optoelectronic device with the electronic interface substrate of the package is complicated due to geometric constraints. The VCSEL emits light in a generally perpendicular direction to the plane of the optical fibers and substrate, therefore making stacking of such components difficult. To solve the packaging problem, the VCSEL is either mounted parallel to the substrate and the output photons directed 90° through mirrors or the VCSEL is mounted perpendicular to the substrate and the electric interface connectors are rotated 90°. The optical bending solution is less than optimal due to the difficult optical design and mirror alignment required. Conversely, the bending of electrical conductors is well known in the art through the implementation of flexible circuits. Therefore, flexible electrical circuits capable of achieving the necessary 90° bend are generally the accepted solution.
There is a need then for a manufacturing method which allows for efficient positioning of the flexible circuit on the electronic interface substrate and maintaining that position during the curing of the adhesive. The problem of alignment and bending of the flexible circuit are exacerbated as data rates of optoelectronic devices increase. Closer connections must be established in order to retain electrical performance levels. The placement and bending of the flexible surface on the substrate is typically performed manually by a skilled technician just prior to application of a bonding adhesive. Unfortunately, the existing techniques employed in connection with this process are time consuming, expensive and prone to failure due to misalignment. If the placement of the flexible circuit fails to align with the substrate connectors, the entire component may need to be scrapped. While manual bending and aligning techniques exist for mounting an optoelectronic device to the substrate, it would be desirable to improve the efficiency and reduce the cost of coupling.